The glass transition temperatures (T-g) of styrene-butyl acrylate copolymers obtained by free radical polymerization in bulk,and in 3 mol . L-1 benzene and benzonitrile solutions, have been measured using differential scanning calorimetry (DSC) to verity the bootstrap effect previously reported for this system. The corresponding values have been correlated with copolymer composition and microstructure using the Johnston equation.